The objective of this proposal is to develop further the kinetic theories of tight-binding inhibitors and statistical methods for the analysis of data, and application of these to known potent drugs, particularly those for actual and potential cancer chemotherapeutic agents such as methotrexate and deoxycoformycin. Computer programs will be developed for fitting curves to experimental points by the method of least squares employing iteration of Newton approximations. Analytical methods thus developed will be applied to the studies of dihydrofolate reductase inhibited by folate analogs and adenosine deaminase inhibited by various compounds such as coformycin, deoxycoformycin, and erythrohydroxynonyl adenine.